The present invention relates to a method for checking data written into buffered write-read memories in numerically controlled machine tools.
In modern automation systems, for instance, in the control of machine tools, the microprocessor has largely replaced hard-wired logic (see, for instance, Siemens-Zeitschrift 1977, No. 8).
Logic operations executed by the system according to a system program are usually permanently programmed in semiconductor memories. In addition to system program memories, storage locations for variable data are further provided in the computer control. Such variable data is entered by operating personnel or by a data carrier and may comprise the entire workpiece program or subprogram routines, and also tool and tool correction data and machine related data. This data is retained by buffer memories during a defined system off-period. Incorrect information in those memories, for instance, because a bit of a semiconductor memory was incorrectly cleared when the system was switched on, or because of a poor soldering joint or a defective plug connection not making contact, can lead to a failure of the entire automation system. In the case of a fault, it is also very difficult for service personnel to localize the affected semiconductor area.